#include<iostream.h>
#include<conio.h>
#include<dos.h>
void main()
{
clrscr();
int port=0,val=0,lowport=0;
char key;
do
{
clrscr();
for(port=lowport;port<lowport+255;port++)
{
  asm{
  mov dx,port
  mov ax,0
  in al,dx
  mov val,ax
  }
 cout<<val<<"\t";
}
key=getch();
if(key==13)
{
 lowport=lowport+255;
}
}
while(key!=27);
}